Electro-pneumatic retarder control

ABSTRACT

The present invention pertains to an electro-pneumatic retarder control (EPRC) valve for a pneumatic retarder that controls the speed of railroad cars in a marshaling yard. The EPRC valve has a housing that generally encloses and protects its various components. The housing has a lid that can be opened to gain access to a control panel mounted on an interior door. The control panel includes a display, keyboard and programmable logic controller or PLC module that can be adjusted to set the desired pressure levels of the retarder. The EPRC valve has a modular pressure control assembly that includes an intake and exhaust manifold, a retarder supply and return manifold and several interchangeable control lines formed by like-shaped control valves and components. A pilot air control assembly enables the PLC module to selectively open and close the control valves and lines to deliver or release pressurized air to the retarder.

This application asserts priority on U.S. Provisional Application Ser.No. 60/485,541 filed Jul. 8, 2003.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to an electro-pneumatic retarder control(EPRC) with a programmable logic controller (PLC) module for controllingthe flow of pressurized air supplied to and discharged from a pneumaticretarder in a railroad marshaling yard.

BACKGROUND OF THE INVENTION

Railroad retarders control the speed of railroad cars in a marshallingyard. Cars sent over the hump of the yard gain speed as they roll downthe hump and are routed via a number of switches to an appropriate trackfor coupling to other cars on that track. The speed of the cars varydepending on the weight of the car, the speed it is sent over the hump,the number of switches and length of track it needs to traverse, thefriction in the wheel bearings of the car, and various other factors.Controlling the speed of the cars is important to ensure the cars arriveat the desired track with an appropriate amount of speed to couple withthe other cars. Too little speed, and the car will not make it wherethey need to go with enough speed to couple with the other cars on thetrack. Too much speed, and the car will jump the track or damage thecoupling mechanisms.

A problem with conventional pneumatic retarder valves is that they aredifficult to maintain. Diagnosing the source of a problem such as themalfunctioning component is difficult. The wrong components arefrequently replaced in a trial and error effort to fix the valve. Thisresults in great expense and frustration, and dramatically increasesdown time.

Another problem with conventional pneumatic retarder valves is thedifficulty adjusting the upper and lower limits of the various pressuresettings for the valve (LIGHT, MEDIUM, HEAVY and EXTRA-HEAVY). Somevalves require the use of a very small screw driver to adjust variableresisters that form the source of the reference voltages that dictatethe desired pressure limits for activating the opening and closing ofthe valve.

A further problem with conventional pneumatic retarder valves is that itis difficult to verify whether or not the pressure transducer isproviding accurate actual retarder pressure information to the valve.The electric signal or pressure data sent by the transducer to thecircuit board is difficult to measure. Although an alternate gage can beused to determine the actual pressure from the retarder cylinders thatis being received at the retarder valve, there is no easy way to verifythat the transducer signal is sending a signal to the circuit board thataccurately corresponds to the actual retarder pressure. Instead ofsimply replacing a failing or faulty pressure transducer, fieldpersonnel attempt to correct the pressure anomalies by adjusting othercomponents such as the variable resisters that set the pressure limits,which fails to correct the underlying problem, can lead to otheroperational problems in the retarder valve and can lead to accident andinjury.

A still further problem with conventional pneumatic retarder valves istheir electrical systems. The systems are polarity sensitive and can bedamaged by inadvertently switching the positive and negative leads.Separate 12 and 24 VDC assemblies are also needed depending on the inputvoltage. Power surges such as by lighting strikes can also easily damagethe electrical system.

A still further problem with conventional pneumatic retarder valves isthat the electronics are difficult to replace. A lightning strike canshut down the control valve for a long time.

A still further problem with conventional pneumatic retarder valves isthat they include valves and other components that require frequentlubrication and other maintenance due to the harsh chemicals found inmarshalling yards.

A still further problem with conventional pneumatic retarder valves isthat they include a large amount of piping and fittings. Thesecomponents frequently leak the pressurized air they are meant tocontain. This leaking waists air, causes the yard compressors to runmore frequently, and reduces the capacity of the pressurized air systemfor the yard.

A still further problem with conventional pneumatic retarder valves isthat many components are exposed to possible damage by parts beingdragged by the railroad cars, the environment and rodents.

The present invention is intended to solve these and other problems.

BRIEF DESCRIPTION OF THE INVENTION

The present invention pertains to an electro-pneumatic retarder control(EPRC) valve for a pneumatic retarder that controls the speed ofrailroad cars in a marshaling yard. The EPRC valve has a housing thatgenerally encloses and protects its various components. The housing hasa lid that can be opened to gain access to a control panel mounted on aninterior door. The control panel includes a display, keyboard andprogrammable logic controller or PLC module that can be adjusted to setthe desired pressure levels of the retarder. The EPRC valve has amodular pressure control assembly that includes an intake and exhaustmanifold, a retarder supply and return manifold and severalinterchangeable control lines formed by like-shaped control valves andcomponents. A pilot air control assembly enables the PLC module toselectively open and close the control valves and lines to deliver orrelease pressurized air to the retarder.

One advantage of the present electro-pneumatic retarder control valve isits modular design, which makes it easy to maintain and repair. Thevalve has easier service pneumatics. Several “at risk” componentsincluding the control valves and their actuating pilot valves arelocated between two manifolds. These components can be removed as asubassembly, and shipped back to the OEM for trouble shooting. Thiseliminates the need for trouble shooting at the yard and reducesequipment down time. The modular nature of the control assembly allows anew subassembly to be quickly installed so that the valve is up andrunning while the faulty subassembly is sent to the OEM for repair. Themanifolds also greatly reduce the number of connections and make theassembly of components much faster. The electronics are also easy toreplace. Quick disconnects between all input wires and the electronicssubassembly facilitate replacement of all electronics in the event of alightening strike.

Another advantage of the present electro-pneumatic retarder controlvalve is the ease with which the upper and lower pressure limits can beentered or modified. The control panel allows the user to both view anyexisting pressure limits on the display, and then simply use the keypadto enter or modify the desired pressure limits for the various weightclasses (LIGHT, MEDIUM, HEAVY and EXTRA-HEAVY). Field personnel simplytype in the desired upper and lower pressure limits for each weightclass. No tools are needed.

A further advantage of the present electro-pneumatic retarder controlvalve is its simple verification of the pressure transducer. The actualretarder pressure sensed by the transducer is converted into a pressuredata signal that is displayed converted into a readable numeric valueand displayed by the control panel. This occurs each time a weight classis requested. The EPRC valve includes a port for attaching an alternatepneumatic or analog pressure gage that is know to be accurate. Thisalternate pressure gage measures the actual pressure being received bythe EPRC valve from the expandable cylinders or chamber of the retarder.Field personnel can easily verify that the pressure transducer isfinctioning properly by comparing the pressure shown in the controlpanel display to the pressure reading of the alternate gage. This allowsfor in service testing of the pressure transducer and helps avoid guesswork in

A still further advantage of the present electro-pneumatic retardercontrol valve is that personnel in the control tower for the yard canremotely determine the presently selected weight class, and remotely setor otherwise modify the weight class setting to a desired weight classsetting.

A still further advantage of the present electro-pneumatic retardercontrol valve is its simple verification that the yard tower command hasreached the valve. Whenever a brake application is requested, the towercommand is displayed on the control panel screen.

A still further advantage of the present electro-pneumatic retardercontrol valve is its adaptable and easy maintenance electrical system.The electrical system is polarity protected. Inadvertent switching ofthe positive or hot lead and the negative or common leads or terminalswill not damage the system or cause it to malfunction. The electricalsystem can also automatically adapt to run on a 12 VDC or a 24 VDC powersupply. This eliminates the need for separate 12 and 24 VDC assemblies.The valve operates satisfactorily over a range of 9-35 VDC. In addition,the electrical system has surge protection. All wires entering the unit,including the 9-35 VDC power, are optically isolated from theelectronics subassembly.

A still further advantage of the present EPRC valve is itslubricant-free design. The assembly has internally protected valves thatare more reliable and do not require lubrication. The valves haveexcellent endurance test results under exposure to harsh chemicals.

A still further advantage of the present electro-pneumatic retardercontrol valve is the simplicity of its pneumatic pressure controlsystem. The manifolds and compact control lines reduce the amount ofpiping and number of fittings so that the opportunities for leaks aregreatly reduced.

A still further advantage of the present EPRC valve is that it providesa protective environment surrounding its working components. Therobustly designed NEMA rated housing protects and seals all the activeworking components from the environment, pieces of railcars that may bedragging, and rodents and insects.

A still further advantage of the present EPRC valve is that it obtains ahigher valve shifting force by using double acting pilot valves. Theforce opening the control valve is not reduced by the force of a returnspring in the pilot valve. In addition, the force produced by the pilotvalve for closing the control valve far exceeds the force supplied by areturn spring.

A still further advantage of the present EPRC valve is that it reducesuser cost by reducing the need for auxiliary exhaust valves. The use ofhigher flow control valves and the capacity of the manifold to accept upto three exhaust valves eliminates the need for auxiliary exhaust valvesfor many retarder applications.

A still further advantage of the present electro-pneumatic retardercontrol valve is its ergonomic design and reduced noise. The air exhaustmufflers are vertically mounted. Air and sound waves are emittedradially or horizontally. The air waves are directed horizontally withina three sided enclosure. The exhaust air does not impact the ground andpropel dust and debris into the air. A three-sided shield also protectsmaintenance personnel from the exhaust air.

A still further advantage of the present EPRC valve is its simple andaesthetically pleasing design. Virtually all the components are enclosedwithin a simple NEMA 4 box or housing with a maintenance access door.Components are not hanging on pipes or under a heavy cover as was doneon previous designs.

A still further advantage of the present EPRC valve is that it is adirect replacement for HS-2, HS-2A, HS-2B, GFV-96, GFV-01 and L&Wretarder valve control assemblies.

Other aspects and advantages of the invention will become apparent uponmaking reference to the specification, claims and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective, cut away view of the present electro pneumaticretarder control (EPRC) valve with its lid and access door open to showits modular control valve assembly.

FIG. 2 is a perspective view of the EPRC valve with the lid open andaccess door closed to show its display and control panel.

FIG. 3 is a top plan view of the display and control panel.

FIG. 4 shows the underside of the interior door, the PLC module andcircuit board of the control panel, and main EPRC heater.

FIG. 4 a is a top plan view of the circuit board of the control panel.

FIG. 5 is an electrical schematic showing the electric power supply tothe control panel, pressure transducer, control valves and heater.

FIG. 6 is a rear view of the EPRC valve in its housing.

FIG. 7 is a front view of the EPRC valve in its housing.

FIG. 8 is a side view of the EPRC valve in its housing.

FIG. 9 is a top plan view of the modular control valve assembly.

FIG. 10 is a top view of the modular control valve assembly.

FIG. 11 is a side view of one of one control line and the manifoldblocks.

FIG. 11 a is an exploded perspective view of one of the large and smallcontrol lines.

FIG. 12 is a bottom view of the intake and exhaust manifold.

FIG. 13 is a side view of the intake and exhaust manifold.

FIG. 14 is a side view of the retarder supply and return manifold.

FIG. 15 is a bottom view of the retarder supply and return manifold.

FIG. 16 is a pneumatic schematic for the control valves and theirassociated pilot valves.

FIGS. 17 a-k show a schematic diagram and legend of the operatingprogram for the EPRC valve.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

While this invention is susceptible of embodiment in many differentforms, the drawings show and the specification describes in detail apreferred embodiment of the invention. It should be understood that thedrawings and specification are to be considered an exemplification ofthe principles of the invention. They are not intended to limit thebroad aspects of the invention to the embodiment illustrated.

The present invention relates to an electro-pneumatic retarder control(EPRC) or control valve assembly generally indicated by reference number10 and shown in FIGS. 1 and 2. The control valve assembly 10 istypically installed within a few feet of a marshalling yard retarder(not shown), which moves its brakes into braking engagement against thewheels of the cars. The valve assembly 10 is divided into four areas orquadrants 11-14. Pressurized air is received by the valve assembly 10via its intake quadrant 11, and controllably delivers the pressurizedair to its supply quadrant 12, which is in pneumatic communication withthe retarder. The pressurized air delivered to the retarder is inpneumatic communication with the return quadrant 13, and controllablyexhausted by the valve 10 to the surrounding atmosphere via the exhaustquadrant 14.

The EPRC or control valve assembly 10 has a housing 20 that generallyencloses the other various components of the assembly. The housing 20 ispreferably elevated from the ground by a support stand (not shown)having a height of about 36 inches. This stand is made of weldedheavy-duty steel to form a weather resistant platform for the housing20. The housing 20 has a top 22 and a bottom 23, and front, rear andsidewalls 24-27 with inside surfaces 28 that form a main compartment 29that preferably has first and fourth areas or quadrants 11 and 14located along the front wall 24, and second and third areas or quadrants12 and 13 located along the rear wall 25. The housing 20 is relativelycompact, and has a length of about 24 inches, a width of about 24 inchesand a height of about 12 inches. The housing 20 and its stand arerobustly designed to retain their shape and integrity during thetypically rugged conditions of a railroad marshalling yard. The housing20 is relatively light with a weight of about 194 pounds without thestand and about 294 pounds with the stand. The housing 20 and stand arepreferably made of thick sheet metal with painted exterior surfaces toinhibit rust and deterioration. The original housing 20 forms a NEMA 4Xrated steel enclosure and it is anticipated that the housing willmaintain its ability to protect internal components from environmentalconditions present in a rail yard.

The housing 20 has an outer door or lid 30 that is movable between open31 and closed 32 positions to gain access to or close and seal theinside compartment 29. The outer access door or lid 30 has upper andlower surfaces 33 and 34. One end of the lid 30 is hinged or otherwiserigidly connected to the top end of one sidewall 27. When the lid 30 isin its open position 31 as in FIGS. 1 and 2, the top 22 of the housingis open. When the lid 30 is in its closed position 32 as in FIGS. 6-8,the top 22 is closed. The outer perimeter of the lid 30 has a downwardlyprojecting rim 36 and an adjacent gasket 37 secured to its lower surface34. The rim 36 flushly engages the outside surface of the top ends ofthe housing walls 24-27 when the lid is in its closed position 32. Thegasket 37 is aligned to mate with and seal against the top ends of thewalls 24-27. The weight of the lid 30 and a latch (not shown) maintainthe lid in its sealed position 32 during use. The seal is sufficientlytight to prevent the entry of dust, humidity and insect infestation intothe compartment 29 of the housing 20 when the lid is in its closedposition 32.

An interior access door 40 is accessible when the outer door or lid 30is in its open position 31. The interior door 40 is also selectivelymovable between open 41 and closed 42 positions to gain access to orclose the inner most portion of the chamber 29. The interior door 40 hasupper or outer surface 43 and lower or inner surface 44. One end of theaccess door 40 is hinged or otherwise rigidly connected to sidewalls 24and 25, in close proximity to sidewall 27. The other end of the door 40has a handle 45. The access door 40 includes an enclosure or recess 46in the upper surface 43. The enclosure 46 has a length of about 10inches, a width of about 10 inch, and a height of about 4 inches. A flatelectric heater 47 a is adhered or otherwise secured to the lowersurface 44 for heating the control panel discussed below. A second morepowerful or main heater 47 b provides sufficient heat to maintain theinterior compartment 29 and various interior components of the assembly10 at or above a necessary or desired working temperature duringoperation in a cold outside environment. The main heater 47 b has itsown internal thermostat for activating and deactivating the heater. Whenthe interior door 40 is in its open position 41 as in FIG. 1, the majorportion of the housing 20 can be accessed through the top 22 of thehousing. When the door 40 is in its closed position 42 as in FIG. 2, themajor portion of the housing 20 is closed. The sidewalls 24-27 of thehousing 20 form a ledge 48 that supports the door 40 when it is in itsclosed position 42. The weight of the interior door 40 maintains it inits closed position 42.

Electric power is delivered to the control valve 10 through aconventional terminal block 50 having a number of individual electricalterminals 52. The terminal block meets AAR standards, and is located onthe lower side 44 of the inner access door 40 toward its hinged end.Electric cables enter the interior compartment 29 of the housing 20through an electric access 55 shown in FIG. 7. This access 55 includes aseal tight connector 56 that inhibits the entry of moisture, dust andinsect infestation into the housing 20. The internal wiring of the EPRCvalve 10 has plug in connectors that provide easy connection of the AARterminal 50.

A user interface or control panel 60 is secured to the upper surface 43of the access door 40 in enclosure 46. The user interface 60 is used toenter setup data or information and monitor operation of the EPRC valve10 as discussed below. The upper surface of the control panel 60 isgenerally flush or even with the remainder of the upper surface 43 ofthe access door 40. The control panel 60 includes a conventional liquidcrystal display 61 and a conventional keyboard 62 with sets of numericalkeys 63, operational keys 64 and functional keys 65 as shown in FIG. 3.The control panel 60 includes a circuit board 67 as in FIG. 4 a thatregulates the power supply to the control panel. The circuit board 67protects the control panel 60 by providing optical isolation of thepower, pressure transducer signal and tower signal via components 68 asin FIG. 5. The valve assembly 10 and its control panel 60 are polarityprotected and operate satisfactorily when the electric power supply isbetween 9 to 35 volts. The valve assembly 10 and control panel 60 alsooperate satisfactorily when outside temperatures are between −44° F. and150° F. The circuit board 67 is in electrical communication with theprogrammable logic controller or PLC module 69 shown in FIG. 4. The PLCmodule 69 includes a processor with an associated memory for storing theoperational programming for the EPRC valve 10 and receiving signals andstoring the data contained in those signals. As discussed below, FIGS.17 a-k show a schematic diagram of the operational programming for theEPRC valve 10, which is in the ladder language.

The LCD display 61 continually indicates the actual pneumatic pressureinside the retarder as long as the control tower for the yard instructsthe EPRC valve 10 to pressurize the retarder when a car passes by theretarder. The control tower can remotely control the valve 10 bypressing the F12 key. The control tower can then set the valve 10 sothat the retarder delivers a LIGHT, MEDIUM, HEAVY or EXTRA-HEAVY amountof braking power when a car passes by the retarder. An operator canmanually override the valve 10 by pressing the F1-F5 keys. The F1 keysets the valve 10 to pressurize the retarder to a LIGHT (about 20 to 30psig) amount of braking power. The F2 key sets the valve 10 topressurize the retarder to a MEDIUM (about 50 to 60 psig) amount ofbraking power. The F3 and F4 keys set the valve 10 to pressurized theretarder to a HEAVY (about 80 to 90 psig) or EXTRA-HEAVY (120 to 145psig or full line pressure) amount of braking power, respectively. TheF5 key opens or discharges the retarder so that it delivers no brakingpower. The desired LIGHT, MEDIUM, HEAVY or EXTRA-HEAVY pressure settingscan be customized using the numeric keys 63 and pressing one of theoperational keys 65.

A modular pressure control assembly or air flow control assembly 70 ishoused in the main compartment 29 of the housing 20 as shown in FIGS. 1,9 and 10. The control assembly 70 operates satisfactorily whencompressed air is delivered to the assembly between about 44 to 147pounds per square inch (psi). The modular control assembly 70 includes afirst manifold block 71 as shown in FIGS. 12 and 13. This manifold block71 takes in pressurized air from the marshalling yard compressed airsystem. The intake block 71 is rigidly secured along the front wall 24in the first and fourth areas or quadrants 11 and 14 of the housing 20.This manifold block 71 has eight bolt holes 71 a for receiving boltsthat rigidly secure it to the housing 20. The manifold 71 has a commonintake channel 72 that is bored a predetermined longitudinal lengththrough one end of the block. The open end of the channel 72 is thenplugged and pneumatically sealed by a cap as shown in FIG. 9. The commonintake channel 72 is in pneumatic communication with an air intakepassage 73 that is bored through the bottom of the manifold block 71,and first and second supply line passages 74 and 75 that are boredthrough the side of the manifold block.

The manifold block 71 preferably exhausts discharged or return air fromthe retarder as discussed below, and is preferably an integral piece ofmetal that forms a combined intake/exhaust manifold block. As such, themanifold block 71 includes first, second and third exhaust passages77-79 for exhausting pressurized air from the retarder to ambientoutside air. Each exhaust passage 77, 78 and 79 includes a first portion77 a, 78 a or 79 a that is bored through the bottom of the block 71, anda second portion 77 b, 78 b or 79 b that is bored through the side ofthe block. Each first portion or bore is in pneumatic communication withand intersects its respective second bore at a right angle. A commonexhaust channel (not shown) may be provided to pneumatically join theexhaust passages 77-79. The bores 74, 75, 77 b, 78 b and 79 b for thesupply and exhaust passages are each spaced apart a predetermineddistance from its adjacent bores.

The modular pressure control assembly 70 includes a second manifoldblock 81 as shown in FIGS. 14 and 15. This manifold block 81 suppliespressurized air to the retarder. The manifold block 81 is positionedalong the rear wall 25 in the second and third areas or quadrants 12 and13 of the housing 20. The supply block 81 includes eight bolt holes 81 afor receiving bolts that rigidly secure it to the housing 20. Themanifold 81 has a common retarder supply channel 82 that is bored apredetermined longitudinal length through one end of the block. The openend of the channel 82 is then plugged and pneumatically sealed by a capas shown in FIG. 9. The common supply channel 82 is in pneumaticcommunication with a retarder supply passage 83 that is bored throughthe bottom of the block, and first and second supply line passages 84and 85 and a first discharge passage 87 that are bored through the sideof the block.

The manifold block 81 preferably receives discharged air from theretarder, and is an integral piece of metal that forms a combinedsupply/return manifold block. As such, the manifold block 81 includessecond and third return passages 88 and 89 that are bored through thebottom surface of the block. Each return passage 88 and 89 includes afirst portion 88 a or 89 a that is bored through the bottom of the block81, and a second portion 88 b or 89 b that is bored through the side ofthe block. Each first portion or bore is in pneumatic communication withand intersects its respective second bore at a right angle. A commonexhaust channel (not shown) may be provided to pneumatically join theexhaust passages 88 and 89. The bores 84, 85, 87, 88 b and 89 b for thesupply and return passages are each spaced apart a predetermineddistance from its adjacent bores.

Although the manifolds 71 and 81 are each shown and described to beintegral blocks of metal that are bolted to the housing, it should beunderstood that the broad aspects of the invention are not limit aparticular manifold shape or form of securement. The manifolds 71 and 81could be integrally formed with the housing or welded to the housing.Similarly, each manifold could be formed by two of more separatecomponents. For example, the intake/exhaust manifold 71 could be formedby two or more components located along the first and second areas orquadrants 11 and 12, and the supply/return manifold 81 could be formedby two or more components located along the second and third areas orquadrants 13 and 14.

External connections 93, 94, 95, 97, 98 and 99 are connected to themanifold blocks 71 and 81 that extend from the exterior surface of thehousing 20 as shown in FIGS. 6-9. An air intake connection 93 passesthrough an opening in the bottom 23 of the housing 20 and into the airintake bore 73 of manifold 71 as shown in FIG. 7. Pressurized airsupplied from the railroad yard compressor (not shown) passes throughthe air intake connection 93 and bore 73 and into the common intakechannel 72. The pressure of the common intake channel 72 is generally atabout 120 psi pressure set by the yard compressor system. A retardersupply connection 94 passes through an opening in the bottom 23 of thehousing toward the rear wall 25 as shown in FIG. 6. The retarder supplyconnection 94 is joined to and is in pneumatic communication with theretarder supply bore 83 and the common channel 82. The retarder supplyconnection 94 delivers pressurized air to the retarder until theretarder is at the desired pressure entered into the control panel 60.Supply connection 94 can also be used to vent air through bore 87. Aretarder return connection 95 passes through the housing 20 and isjoined to and in pneumatic communication with the second discharge bore88. Air being discharged from the retarder to release its brakemechanism is discharged into retarder connection 95 and second dischargebore 88. The air being discharged from the retarder can also be routedthrough an additional return line to a second retarder return connectionthat is joined to and pneumatically in communication with the thirddischarge bore 89. Three air exhaust connections 97, 98 and 99 arejoined to and in pneumatic communication with exhaust bores 77, 78 and79, respectively. Intake connection 93, supply/return connection 94 andreturn connections 95 and 96 include a ninety degree elbow 93 a, 94 a,95 a or 96 a. Each exhaust connection 97-99 includes a muffler 97 a, 98a or 99 a. A three-sided shield (not shown) is provided to protect filedpersonnel for the exhaust air.

A number of control lines 100 extend between the intake and exhaustmanifold block 71 and the retarder supply and discharge manifold block81. Each control line 100 has the same overall length, has a similarin-line shape and includes similar or like-shaped components. Eachcontrol line 100 includes piping 101, first and second couplings 102 and103, an expansion joint 104 and a valve 105. Each coupling 102 and 103includes bolts 102 a or 103 a that rigidly secure the line to themanifolds 71 and 81 via their bolt holes 102 b or 103 b, respectively.Two control lines 100 are supply lines 111 and 112. Supply line 111 isin pneumatic communication with the first supply line bores 74 and 84 ofthe manifolds 71 and 81, respectively. Supply line 112 is in pneumaticcommunication with second supply line bores 75 and 85. Supply line 111has similar but smaller diameter components 101-105 than those in lines112-115. The smaller line 111 has a diameter of ¾ inches and the largerline 112 has a diameter of 1½ inches. Discharge lines 113, 114 and 115also extend between the intake and exhaust manifold block 71 and theretarder supply and discharge manifold block 81. The discharge lines113-114 have identical components 101-105 and an equivalent length tothe supply line 112. Lines 112-115 are interchangeable, and have adiameter of 1½ inches. Discharge line 113 is in pneumatic communicationwith exhaust bores 77 and 87. Discharge line 114 is in pneumaticcommunication with exhaust bores 78 and 88. The optional third dischargeline 115 is in pneumatic communication with discharge bores 79 and 89.

The programmable logic controller or PLC module 69 of the control panel60 regulates the volumetric delivery of air to the retarder bycontrolling the flow of air through the smaller and larger supply lines111 and 112. When both supply lines 111 and 112 are closed, nopressurized air is delivered to the retarder. When only the smallersupply line 111 is open, pressurized air is delivered to the retarder ata smaller volumetric rate. The smaller supply line 111 increases theactual pressure in the retarder more slowly so that the control valve 10has more control over the actual pressure in the retarder valve. Thishelps prevent the control valve 10 from overshooting this relatively lowor light desired pressure. Only the smaller supply line 111 is typicallyopened to pressurize the retarder to a LIGHT (about 20 to 30 psig) orMEDIUM (about 50 to 60 psig) weight class or amount of actual pressureor braking power. The volumetric rate of flow of pressurized air to theretarder increases when the larger supply line 112 is open and thesmaller supply line 111 is closed. An even greater volumetric rate offlow of pressurized air is delivered to the retarder when both supplylines 111 and 112 are opened. Only the large supply line 112 istypically opened to pressurize the retarder to a HEAVY (about 80 to 90psig) or EXTRA-HEAVY (about 120 to 145 psig) weight class. The selectedweight class dictates the amount of actual pressure or braking powersupplied by the EPRC valve to the expandable cylinders in the retarder.The preferred PLC module 69 is made by Homer Electric of CIMTECAutomation and Control of Charlotte N.C. and sold as Part No.HE500OCS210.

Each control line 111-115 includes a conventional pneumatically operatedvalve 121-125. The valves 121-125 are designed to allow the pressurizedair to flow through them in a particular direction 130. Supply lines 111and 112 have their supply valve 121 and 122 facing so that compressedair can flow from the common intake chamber 72 in the intake and exhaustmanifold block 71 to the common supply chamber 82 in retarder supply andreturn manifold block 81. Although discharge lines 113-115 areinterchangeable with supply line 112, they have their discharge valves123-125 facing in an opposite direction so that air flows from thereturn side of the supply and return manifold block 81 to the exhaustside of the intake and exhaust manifold 71 block as shown in FIGS. 9 and10. Each line 101-105 could be replaced by a pre-assembled like lineformed by the same components 101-105 and adjusting expansion joint 104to accommodate its precise fitting and connection between the manifoldblocks 71 and 81.

Each valve 121-125 is controlled by a separate pilot air valve 141 asshown in FIGS. 10 and 16. Each pilot air valve 141 has an electricsolenoid 142 that is controlled by the central processing unit of theprogrammed logic controller 69 in the control panel 60 as shown in FIG.4. The pilot air valve 141 and solenoid 142 work in combination todirect pressurized pilot air to one of two sides of a piston in itscorresponding valve 121-125 to move that valve into either an open orclosed position. The pilot air valves 141 and solenoids 141 arepreferably manufactured by Festo Corporation of Germany as Model NumberMFH-5-1/4-MA. Each valve 121-125 is either open or closed. When eitheror both valves 121 and 122 of supply lines 111 or 112 are open, then thevalves 123-125 of discharge lines 113-115 are closed. This deliverspressurized air to the retarder. Pressurized air is delivered to theretarder until the pressure in the cylinders of the retarder reach thepre-established pressure for the desired light, medium, heavy or extraheavy braking power setting. Actual pressure in the retarder ispneumatically communicated via a tube 146 to a pressure transducer 145mounted on manifold block 81.

The pressure transducer 145 monitors the pressure in the retardercylinders. The pressure transducer 145 is located in the maincompartment 29 a of the housing 20, and is connected to and in pneumaticcommunication with the retarder cylinder via a ⅜ inch hose. The retardercylinder reservoir dampens the reaction of the transducer 145 whensudden changes in air pressure occur. The transducer 145 converts thepressure to a corresponding 4 to 20 mA electric signal that is sent viaa wire 147 to the processor of the PLC module 69 located in the controlpanel 60. The pressure transducer 145 is capable of measuring between 0to 145 psi, which is greater than the yard compressed air system. Thesignal sent to the PLC module 69 is directly proportional to the airpressure in the retarder cylinder. The transducer 145 sends a 4 mAsignal when there is zero pressure in the cylinder. Each additional 1 mAsignal strength is equal to about 9 psi more air pressure in thecylinder. In this way, the PLC module 69 is constantly receiving actualpressure data from the retarder to compare to the stored upper and lowerpressure limit setting (20 to 30 psig, 50 to 60 psig, 80 to 90 psig, or120 to 145 psig) for the currently selected braking power or weightclass setting (LIGHT, MEDIUM, HEAVY or EXTRA-HEAVY). The programmedprocessor 69 will then open and close the inlet and exhaust valves121-125 to ensure that the retarder pressure stays within the desiredweight class specification. If desired, the EPRC valve 10 can beconfigured to send the 4 to 20 mA signal of the transducer 145 directlyto the yard's computer system.

The control panel 60 has a temperature transducer 148 in its circuitboard 67 as shown in FIG. 4 a. The temperature transistor 148 monitorsthe actual temperature in the control panel 60, and is wired to the PLCmodule 69. The transistor 148 generates and sends a signal containingthis actual temperature data to the PLC module 69. The PLC module 69 andprogram use this temperature data to turn on and off the flat heater 47a secured to the underside 44 of the recess 46 of the interior door 40as shown in FIG. 1. This allows the PLC module 69 and program toautomatically elevate the temperature in the control panel 60 above rthe temperature of the interior 29 of the EPRC valve 10 to help ensureproper operation of the control panel.

When the actual pressure in the retarder as measured by the transducer145 reaches the pre-established or desired amount of pressure (LIGHT,MEDIUM, HEAVY or EXTRA-HEAVY braking power) stored in the memoryassociated with the processor of the PLC module 69, the programmedprocessor causes the solenoid 142 and pilot valve 141 to close valves121 and 122 to stop further delivery of pressurized air to the retarder.When all the valves 121-125 are closed, the pressurized air in theretarder is retained and the pressure is maintained at that actualpressure. Should the processor of the PLC module 69 detect via thepressure transducer 145 that the actual pressure in the retarder hasdropped due to a leak in the retarder or the supply lines to theretarder, one or both valves 121 and 122 of supply lines 111 and 112 canbe reopened to elevate the actual pressure back to the desired pressure.The valves 123-125 of discharge lines 113-115 are opened to dischargethe pressurized air in the retarder so that the retarder is in an openor non-braking position. The pressurized air in the supply line to theretarder is exhausted through discharge line 113 and muffler 97 a. Thedischarge line or lines of the retarder are exhausted through dischargelines 114 or 115 and corresponding mufflers 98 a or 99 a.

A conventional pilot air assembly 150 is used in combination with thepilot valve 141 and solenoid 142 to control the opening and closingoperation of the valves 121-125 as shown in FIG. 16. The pilot airassembly 150 includes an air intake line or tube 152 with an intake port153 secured to a passage or bore 154 in manifold 71. The intake line 152is in pneumatic communication and takes pressurized pilot air from thecommon intake channel 72 to open and close the valves 121-125. Theintake line 152 includes a set of filters 155 for removing impuritiesbefore the pilot air header branches off to the five pilot valves 141. Abranch of the air intake line 152 is pneumatically connected to anintake port of each pilot valve 141. The pilot air assembly 150 alsoincludes an air exhaust line or tubing 163 connected to an outlet portfor each pilot valve 141, which is exhausted to ambient outside air.Each exhaust line 163 includes an exhaust filter 165 that preventsmoisture, dust and insects from entering into the pneumatic controlassembly 150. Although not shown, the exhaust tubing 163 can feed into acommon header prior to exhausting to ambient outside air.

Setup and Operation

An operating program is downloaded or otherwise entered into theassociated memory of the PCL module 69 during assembly. When theinstalled program is booted-up or uploaded, the control panel 60 is usedto load default variables, such as the number of exhaust valves, thetemperature to trigger heater operation, upper and lower pressure limitsfor each weight class. The program allows these values to be accessed,entered or modified via the user interface 60 so that personnel at agiven railroad marshalling yard can customize these variables for theiryard and desired operation. Still, these values are initially loadedduring assembly so that manufacturing and quality personnel can verifyoperation of the EPRC valve 10 and so that field personnel can operatethe unit 10 prior to entering their specific information.

A schematic diagram of the operating program is shown in FIGS. 17 a-j,which includes a legend in FIG. 17 k. The program begins (200, 205) byscaling the signals from the pressure transducer 145 and temperaturetransducer (not shown) so that this actual pressure and temperatureinformation can be displayed in recognizable units, such as psi and ° F.These values are displayed on the LCD display 61 so that field personnelcan verify proper operation. The program then determines if a LIGHTweight class command or power setting was given (210, 215). If a LIGHTcommand was given, the program then determines if any of the valves121-125 need to be actuated to adjust the pressure in the retarder to aLIGHT setting. The upper and lower pressure limit of each power settinghas a dead band of about 2 psi to prevent sporadic operation of thepilot valves 141 at these pressure limits caused by fluctuations in theactual pressure in the retarder or the signal sent from the pressuretransducer 145. The PLC module and program do not send a signal to thepilot valve or alter the open or closed state of the control valve whenthe actual pressure data from the transducer is within the dead band.When the actual pressure in the retarder is at or approaches one of thepressure limits of the user specified range, the dead band preventsthese fluctuations in the signal or air pressure from causing the PLCmodule 69 to send signals to the pilot valves 141 to open and close soquickly that the main valves do not cycle but pilot valve actuationoccurs. The dead band at the upper and lower pressure limits preventsthis unwanted cycling and wear of the pilot valves 141. A portion of theprogram logic (210 to 315) includes the commands for setting theselimits. If the actuation of valve 121-125 is deemed necessary by the PLCmodule 69 when it compares the actual retarder pressure data receivedfrom the pressure transducer 145 to the desired upper of lower limitsfor the presently selected weight class or power setting, the value ofTBIT1 (290) or TBIT2 (315) will be changed to indicate if pressurizedair form the yard compressed air system needs to be added to theretarder or exhausted from the retarder. The program logic (210 to 315)for determining if the LIGHT power setting command requires valve121-125 actuation is then repeated for each of the other weight classes(MEDIUM—TBIT3 or TBIT4, HEAVY—TBIT5 or TBIT6 or EXTRA HEAVY—TBIT7 orTBIT8).

Program logic (325 to 340) determines if the PLC module 69 is instructedto be in TOWER or MANUAL mode. When in TOWER mode, the EPRC valve 10does not respond to any MANUAL commands. This is important because thevalve 10 is being used to control the speed of railcars being assembledinto trains when in the TOWER mode. An accident or derailment couldoccur if the valve 10 responded to an accidental MANUAL command. When inMANUAL mode, the valve 10 does not respond to TOWER commands. This isimportant because the MANUAL mode is implemented by retarder servicemenmaintaining or repairing the EPRC valve 10 or its associated retarder.If the valve 10 were to respond to an accidental TOWER command while inMANUAL mode, servicemen could be injured.

The next step in the program is to determine if a valid LIGHT commandhas been given. For there to be a valid TOWER LIGHT command (345), thePLC module 69 must be in TOWER (AUTO) mode, the control tower must berequesting a LIGHT power or weight class setting, the upper and lowerpressure limits for the weight classes must be reasonable (upper limitof pressure range must be above lower limit of pressure range), and thetower must not be requesting any other weight classes. Experience withthis equipment has revealed that, as a result of either poor controlsystem programming, damaged wiring or lightening protection systems, itis possible for the unit to receive signals to go to multiple weightclasses at the same time. If this occurs, the operating program will notacknowledge the signals until a single signal is received. Similarprogram logic (355) is used to determine if a valid MANUAL LIGHT signalhas been received. The program logic (345 to 360) is then repeated foreach of the other weight classes to verify if a valid TOWER or MANUALsignal has been received.

The program (370, 375) determine if the ¾ inch inlet valve 121 should beopened, and then (380) sends a signal to actuate the pilot valve 141 andopen the valve 121. The program will not send a signal to thecorresponding pilot valve 141 to open valve 121 unless the actualpressure in the retarder is below both the user specified lower limit ofthe selected weight class and the dead band established for that lowerlimit. The ¾ inch valve 121 is only used to allow air into the retarderduring a LIGHT or MEDIUM command. A smaller flow rate and amount ofpressurized air from the yard system is required to achieve these twoweight classes in an adequate response time. Use of the larger inletvalve 122 may result in the pressure in the retarder rising too quickly,which could cause retarder pressure to exceed the maximum pressure forthe weight class before the inlet valve 122 has a chance to close. Theprogram (385 to 395) determines if the 1½ inch inlet valve 122 should beopened. This portion of the program is similar to portion (370 to 380)except for the HEAVY and EXTRA HEAVY weight classes. The 1½ inch valve122 is used when a rapid inrush of pressurized air is needed to bringthe retarder up to the desired pressure.

The program (400 to 420) determines if the exhaust valves 123-125 needto be opened because either the upper limit and dead band pressure for aweight class is exceeded or a valid TOWER OPEN command is received. Theprogram (425 to 435) determines if a valid MANUAL OPEN command isreceived. The program is configured so that the unit 10 will respond toeither a continuous or momentary depression of the OPEN button. However,the PLC must be in MANUAL mode and no other MANUAL commands may beactive. The program (440 to 485) determines how many exhaust valves123-125 the user has told the PLC are in the unit 10 and activates thosevalves if a valid OPEN signal is received.

While the invention has been described with reference to a preferredembodiment, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted withoutdeparting from the broad aspects of the invention.

1. A modular retarder control valve for selectively controlling a flowof pressurized air supplied to and discharged from a pneumatic retarderin a railroad marshaling yard, said marshalling yard having a compressorproducing a pressurized air supply, said modular retarder control valvecomprising: a housing having an interior compartment with intake,exhaust, supply and return quadrants, said intake and exhaust quadrantsforming an intake/exhaust section and said supply and return quadrantsforming a supply/return section; said intake quadrant having an intakepathway for receiving pressurized air from the pressurized air supply ofthe yard, said exhaust quadrant having an exhaust pathway for exhaustingthe air from said retarder, said intake/exhaust section having a firstset of ports including first, second and third matable ports, saidintake pathway being in pneumatic communication with at least one ofsaid matable ports, and said exhaust pathway being in pneumaticcommunication with at least one other of said matable ports; said supplyquadrant having a supply pathway for supplying the pressurized air tosaid retarder, said return quadrant having a return pathway forreturning air from said retarder, said supply/return section having asecond set of ports including first, second and third matable ports,said supply pathway being in pneumatic communication with at least oneof said matable ports, and said return pathway being in pneumaticcommunication with at least one other of said matable ports; and, first,second and third control lines, each of said control lines forming aseparate flow path and having a control valve selectively movablebetween open and closed positions to control the flow of the pressurizedair along its said flow path, said control lines using interchangeablefastening mechanisms to releasably secure said control lines to saidmodular retarder control valve, said first control line pneumaticallyconnecting said first matable port of said intake/exhaust section tosaid first matable port of said supply/return section, said secondcontrol line pneumatically connecting said second matable port of saidintake/exhaust section to said second matable port of said supply/returnsection, and said third control line pneumatically connecting said thirdmatable port of said intake/exhaust section to said third matable portof said supply/return section.
 2. The modular retarder control valve ofclaim 1, and wherein said intake/exhaust section has a intake/exhaustmanifold and said supply/return section has a supply/return manifold,said intake and exhaust pathways and first set of ports are formed bysaid intake/exhaust manifold, said supply and return pathways and secondset of ports are formed by said supply/return manifold.
 3. The modularretarder control valve of claim 2, and wherein said manifolds are fixeda predetermined distance apart with said first set of ports beingdiametrically opposed to said second set of ports, and each of saidcontrol lines extends between said manifolds, said control line havingan expansion joint between its opposed ends to facilitate the releaseand securement of said control line to said manifolds.
 4. The modularretarder control valve of claim 3, and wherein said manifolds formfacing parallel surfaces, and said matable ports are located at evenlyspaced distances along said parallel surfaces, each mating port in saidintake/exhaust manifold has a corresponding mating port in saidsupply/return manifold that is located directly opposite, and each ofsaid control lines being perpendicular to said parallel surfaces of saidmanifold blocks.
 5. The modular retarder control valve of claim 4, andwherein at least two of said control lines have a substantially equallength and are interchangeable.
 6. The modular retarder control valve ofclaim 5, and wherein each of said control valves is a pneumaticallyoperated valve that allows pressurized air to flow in one directionalong its said flow path.
 7. The modular retarder control valve of claim5, and wherein each of said interchangeable fastening mechanisms is alike-shaped flange and bolt assembly that is matingly received aroundone of said matable ports.
 8. The modular retarder control valve ofclaim 4, and wherein said intake/exhaust manifold has a fourth matableport, said supply/return manifold has a fourth matable port, and furtherincluding a fourth control line that pneumatically connects said fourthmatable port of said intake/exhaust manifold to said fourth matable portof said supply/return manifold.
 9. The modular retarder control valve ofclaim 8, and wherein said intake/exhaust manifold has a fifth matableport, said supply/return manifold has a fifth matable port, and furtherincluding a fifth control line that pneumatically connects said fifthmatable port of said intake/exhaust manifold to said fifth matable portof said supply/return manifold.
 10. The modular retarder control valveof claim 2, and wherein each of said manifolds is an integral block. 11.The modular retarder control valve of claim 2, and wherein each of saidmanifolds is formed by two separate blocks, each separate block beingfixed to said housing in an aligned manner.
 12. The modular retardercontrol valve of claim 1, and wherein each control valve is actuated bya separate pilot air valve.
 13. The modular retarder control valve ofclaim 12, and wherein each pilot air valve is actuated by an electricsolenoid.
 14. The modular retarder control valve of claim 13, andwherein said pilot air valve and electric solenoid work in combinationto direct pressurized pilot air to one of two sides of a piston in eachcorresponding control valve to move that valve into either said open orsaid closed position.
 15. A retarder control valve for selectivelycontrolling a flow of pressurized air supplied to and discharged from apneumatic retarder in a railroad marshaling yard, the marshalling yardhaving a compressor producing a pressurized air supply, said retardercontrol valve comprising: an air flow control assembly having intake,supply, return and exhaust pathways, a supply valve positioned betweensaid intake and supply pathways, and an exhaust valve positioned betweensaid return and exhaust pathways, said valves being selectively movablebetween open and closed positions, said intake pathway receivingpressurized air from the compressor, said supply pathway supplyingpressurized air to the retarder when said supply valve is in said openposition, said return pathway discharging pressurized air from theretarder, and said exhaust pathway exhausting discharged pressurized airfrom said control assembly when said exhaust valve is in said openposition; a processor in communication with input and output terminalsand an associated memory, said output terminals being in communicationwith said control valves; a pressure receiving device in communicationwith the retarder and one of said terminals of said processor, saidpressure receiving device obtaining actual pressure information from theretarder and transmitting actual pressure data to said processor; a userinterface in communication with said memory, said user interface beingoperable to receive desired pressure level information and send desiredpressure data to said memory, said desired pressure data forming adesired pressure range; and, wherein said processor compares said actualpressure data to said desired pressure data, and said processor isprogrammed to selectively open and close said valves to maintain saidactual pressure data within said desired pressure range by selectivelyopening and closing said valves to control said flow of the pressurizedair to and from the retarder.
 16. The retarder control valve of claim15, and wherein said user interface has a control panel with a keyboardhaving keys for inputting said desired pressure information, and adisplay (61) that displays said actual pneumatic pressure information inreal-time.
 17. The retarder control valve of claim 15, and wherein saidkeyboard includes keys for inputting additional operational information.18. The retarder control valve of claim 15, and further comprising acommunication port for downloading a program to said memory of saidprocessor.
 19. The retarder control valve of claim 18, and wherein saidprogram provides a plurality of weight class settings, each weight classsetting having an upper desired pressure limit and a lower desiredpressure limit, said keyboard being operable to enter said upper andlower desired pressure limits.
 20. The retarder control valve of claim19, and wherein said program allows for said weight class settinginclude light, medium, heavy and extra heavy weight classes.
 21. Theretarder control valve of claim 15, and further comprising an electricterminal block for supplying electric power to said processor and userinterface.
 22. A retarder control valve for selectively controlling aflow of pressurized air supplied to and discharged from a pneumaticretarder in a railroad marshaling yard, the yard having a compressorproducing a pressurized air supply, said arrangement comprising: ahousing having bottom and side portions that are integrally andseamlessly joined to collectively define an interior compartment sealedby a lid, said lid being movable between an open position to gain accessto said interior compartment and a closed position to form a NEMA ratedenclosure protecting said interior compartment from damage by passingrailroad cars and infiltration of rail yard and environmental elements;an interior access door disposed between said lid and said bottomportion, said internal access door being selectably movable between araised position to gain access to main compartment and a closedposition; an air flow control assembly having intake, supply, return andexhaust pathways formed by opposed manifolds, a supply valve positionedbetween said intake and supply pathways, and an exhaust valve positionedbetween said return and exhaust pathways, each of said valves beingselectively movable between open and closed positions, said supplypathway receiving pressurized air from the compressor, said supplypathway supplying pressurized air to the retarder when said supply valveis in said open position, said return pathway receiving discharge airfrom the retarder, and said exhaust pathway exhausting discharged airfrom said control assembly when said exhaust valve is in said openposition; and, a control panel providing operative control of saidvalves and flow of the pressurized air to and from the retarder, saidcontrol panel being positioned on said access door, and said controlpanel being accessible when said interior access door is in its saidclosed position.
 23. The retarder control valve of claim 22, and whereinsaid lid has a continuous downwardly projecting rim and an interiorgasket adjacent said rim that seals against a top perimeter of said sideportions when said lid is in said closed position.
 24. The retardercontrol valve of claim 22, and wherein said housing has a front a rear,and opposed sides, and said lid is hingably attached to a top end of oneof said opposed sides and includes an upwardly extending handle on saidother opposed side, and said interior access door is hingably attachedalong one of said opposed sides and an upwardly extending handle on saidother opposed side.
 25. The retarder control valve of claim 22, andfurther comprising a thin electric heating pad disposed on a lowersurface of said interior access door for providing heat to said interiorcompartment.
 26. The retarder control valve of claim 22, and whereinsaid side portions form an interior ledge that supports said interioraccess door when said interior access door is in said closed position.27. The retarder control valve of claim 22, and wherein said housingcomprises an electric access for receiving electric cables, and saidelectric access has a seal tight connector.
 28. The retarder controlvalve of claim 22, and wherein said control panel is mounted in a recessformed in an upper surface of said interior access door.
 29. A retardercontrol valve for selectively controlling a flow of pressurized airdelivered to and released from a pneumatic retarder in a railroadmarshaling yard, the marshalling yard having a compressor producing apressurized air supply, said retarder control valve comprising: ahousing forming an interior compartment and having first, second andthird exhaust bores; an air flow control assembly located in saidinterior compartment, said control assembly having an intake pathway, asupply pathway, first and second return pathways, first, second andthird exhaust pathways, and first, second, third and fourth controllines, each control line forming a flow path and having a control valveselectively movable between open and closed positions to control theflow of pressurized air through its said flow path, said intake pathwayreceiving pressurized air from the compressor, said supply pathwaysupplying pressurized air to the retarder when said supply valve is insaid open position, said return pathway discharging pressurized air fromthe retarder, and each of said exhaust pathways exhausting dischargedpressurized air from said control assembly when its said exhaust valveis in said open position, said first control line pneumaticallyconnecting said supply pathway with said first exhaust pathway and firstexhaust bore, said second control line pneumatically connecting saidfirst return pathway with said second exhaust pathway and second exhaustbore, and said third control line pneumatically connecting said secondreturn pathway with said third exhaust pathway and third exhaust bore,said fourth control line pneumatically connecting said intake and supplypathways; wherein the pressurized air discharged from the retarder andsaid supply pathway is exhausted through said first, second and thirdexhaust pathways and their respective exhaust bores via said first,second and third control lines to rapidly reduce the pressure in theretarder.
 30. The retarder control valve of claim 29, and wherein saidfirst second and third exhaust pathways share a common exhaust pathway.31. The retarder control valve of claim 29, and wherein said returnpathways share a common return pathway.
 32. The retarder control valveof claim 29, and further comprising a fifth control line pneumaticallyconnecting said intake and supply pathways, said fifth control linehaving a smaller volumetric flow rate than said fourth control line. 33.The retarder control valve of claim 29, and further comprising first,second, and third air exhaust connections connected to the respectivesaid first, second and third air exhaust bores.
 34. The retarder controlvalve of claim 33, and further comprising an intake bore and connection,a supply bore and connection and a return bore and connection, saidintake bore and connection passing through said housing and in pneumaticcommunication with said intake pathway, said retarder supply bore andconnection passing through said housing and in pneumatic communicationwith said supply pathway, said retarder return bore and connectionpassing through said housing and in pneumatic communication with saidreturn pathway.
 35. An ergonomic retarder control valve for selectivelycontrolling a flow of pressurized air delivered to and released from apneumatic retarder in a railroad marshaling yard, the yard having acompressor producing a pressurized air supply, said ergonomic retardercontrol valve comprising: a housing having an interior compartment andcomprising a pressure control assembly having an intake pathway forreceiving pressurized air, a supply pathway for supplying pressurizedair to the retarder, a return pathway for receiving pressurized air fromthe retarder, and an exhaust pathway for exhausting pressurized air fromthe retarder; said pressure control assembly further comprising aplurality of control lines, each control line forming a flow path andhaving a control valve that is selectively movable between open andclosed positions to control the flow of the pressurized air along itsrespective said flow path, wherein a first control line of saidplurality of control lines pneumatically connects said intake pathway tosaid supply pathway to control pressurized air flow from said intakepathway to said supply pathway, a second control line of said pluralityof control lines pneumatically connects said return pathway to saidexhaust pathway to control pressurized air flow from said return pathwayto said exhaust pathway, a third control line of said plurality ofcontrol lines pneumatically connects said return pathway to said exhaustpathway to control pressurized air flow from said return pathway to saidexhaust pathway, and a fourth control line of said plurality of controllines pneumatically connects said return pathway to said exhaust pathwayto control pressurized air flow from said return pathway to said exhaustpathway; first, second and third air exhaust bores formed in saidhousing and pneumatically connected to said exhaust pathway; wherein thepressurized air released from said retarder is exhausted through theexhaust pathway and the first, second and third exhaust bores via thefirst, second and third control lines; first, second, and third airexhaust connections connected to the respective said first, second andthird air exhaust bores; and exhaust mufflers connected to and extendingvertically from each of said first, second, and third air exhaustconnections such air and sound waves are emitted radially orhorizontally with respect to said housing.
 36. The ergonomic retardercontrol valve of claim 35, and further comprising a shield for blockingair and sound waves emitted from the exhaust mufflers.
 37. A programmedretarder control valve for selectively controlling a flow of pressurizedair delivered to and released from a pneumatic retarder in a railroadmarshaling yard, the yard having a compressor that produces apressurized air supply, said programmed retarder control valvecomprising: an air flow control assembly having an intake pathway forreceiving pressurized air from the yard, a supply pathway for supplyingpressurized air to the retarder, a return pathway for receivingpressurized air from the retarder, an exhaust pathway for exhaustingpressurized air from the retarder, and a control valve assembly thatcontrols the flow of pressurized air through said intake and supplypathways to the retarder and the flow of pressurized air through thereturn and exhaust pathways from the retarder; a user interface having akeyboard, said user interface allowing operable entry of a desiredpressure limit information and sending a signal containing correspondingdesired pressure limit data; a pressure transducer in communication withthe retarder, said pressure transducer obtaining actual retarderpressure information from the retarder and sending a signal containingcorresponding actual retarder pressure data; a processor incommunication with an associated memory, said memory including anoperating program and being in communication with said user interface toreceive and store said desired pressure limit data, said processor beingin communication with said pressure transducer to receive said actualretarder pressure data; and, wherein said processor compares said actualretarder pressure data with said desired pressure limit data, and basedon said comparison said processor operates said control valve assemblyto open and close said pathways in said air flow control assembly toallow the flow of pressurized air one of either to and from the retarderuntil said actual retarder pressure data approaches said desiredpressure limit data.
 38. The programmed retarder control valve of claim37, and wherein said air flow control assembly includes a plurality ofcontrol lines, each forming a flow path and having a control valve thatis selectively movable between open and closed positions to control theflow of the pressurized air along its respective said flow path, whereina first control line of said plurality of control lines pneumaticallyconnects said intake pathway to said supply pathway to controlpressurized air flow from said intake pathway to said supply pathway,and a second control line of said plurality of control linespneumatically connects said return pathway to said exhaust pathway tocontrol pressurized air flow from said return pathway to said exhaustpathway.
 39. The programmed retarder control valve of claim 37, andwherein said air flow control assembly includes a plurality of pilot airvalves for controlling said control valves and for selectively movingeach of said control valves between said open and said closed positionsto control the flow of the pressurized air along its said flow path. 40.The programmed retarder control valve of claim 37, and wherein each ofsaid control valves allows the flow of pressurized air in one directionalong its said flow path.
 41. The programmed retarder control valve ofclaim 37, and wherein said program provides light, medium, heavy, orextra-heavy weight classes, and allow for the selection of one of saidweight classes as a currently selected weight class, and said userinterface is used to enter desired upper pressure limit information anddesired lower pressure limit information for each of said weightclasses, and said user interface sends signals containing correspondingdesired upper pressure limit data and desired lower pressure limit datato said memory for each of said weight classes; and, wherein saidprocessor compares said actual retarder pressure data with said desiredupper pressure limit data and said desired lower pressure limit data forsaid currently selected weight class, and based on said comparison saidprocessor operates said control valve assembly to open and close saidpathways in said air flow control assembly to allow the flow ofpressurized air one of either to and from the retarder until said actualretarder pressure data approaches one of either said desired upperpressure limit data and said desired lower pressure limit data of saidcurrently selected weight class.
 42. The programmed retarder controlvalve of claim 41, and wherein said first control line is a smalldiameter supply line, and said processor selectively opens only saidfirst small control line to deliver pressurized air to said retarderwhen said selected weight class is one of either said light and mediumweight classes until said actual retarder pressure data substantiallyequals said desired upper pressure limit data for said selected weightclass.
 43. The programmed retarder control valve of claim 41, andwherein said second control line is a large diameter supply line, andsaid processor selectively opens only said second large diameter controlline to deliver pressurized air to said retarder when said selectedweight class is one of either said heavy and extra-heavy weight classesuntil said actual retarder pressure data substantially equals saiddesired upper pressure limit data for said selected weight class. 44.The programmed retarder control valve of claim 41, and wherein one ofeither said processor and its associated memory is in communication witha control tower, and said program permits said control tower to selectsaid currently selected weight class.
 45. The programmed retardercontrol valve of claim 37, and wherein said processor and its saidprogram allow one of either local operative control of said retardercontrol valve via said user interface or remote operative control ofsaid retarder control valve via another location.
 46. The programmedretarder control valve of claim 37, and wherein said programmed retardercontrol valve is automatically controlled by said processor and saidprogram until overridden via said user interface.
 47. The programmedretarder control valve of claim 37, and wherein each control valve iscontrolled by a separate pilot air valve.
 48. The programmed retardercontrol valve of claim 47, and wherein each pilot air valve has anelectric solenoid controlled by said processor.
 49. The programmedretarder control valve of claim 48, and wherein said pilot air valve andelectric solenoid work in combination to direct pressurized pilot air toone of two sides of a piston in each corresponding control valve to movethat said control valve into either the open or the closed position. 50.The programmed retarder control valve of claim 37, and wherein saidprocessor is a programmable logic controller.
 51. A modular retardercontrol valve for selectively controlling a flow of pressurized airsupplied to and discharged from a pneumatic retarder in a railroadmarshaling yard, said marshalling yard having a compressor producing apressurized air supply, said modular retarder control valve comprising:a housing having an interior compartment containing an intake/exhaustmanifold, a supply/return manifold and first, second and third controllines positioned between said manifolds; said intake/exhaust manifoldhaving an intake pathway for receiving pressurized air from thepressurized air supply of the yard and an exhaust pathway for exhaustingthe air from said retarder, said intake/exhaust manifold having a firstset of ports including first, second and third matable ports, saidintake pathway being in pneumatic communication with at least one ofsaid matable ports, and said exhaust pathway being in pneumaticcommunication with at least one other of said matable ports; saidsupply/return manifold having a supply pathway for supplying thepressurized air to said retarder and a return pathway for returning airfrom said retarder, said supply/return manifold having a second set ofports including first, second and third matable ports, said supplypathway being in pneumatic communication with at least one of saidmatable ports, and said return pathway being in pneumatic communicationwith at least one other of said matable ports; and, said first, secondand third control lines, each of said control lines forming a separateflow path and having a control valve selectively movable between openand closed positions to control the flow of the pressurized air alongits said flow path, said control lines using interchangeable fasteningmechanisms to releasably secure said opposed ends of each said controlline to said intake/exhaust and supply/return manifolds, said firstcontrol line pneumatically connecting said first matable port of saidintake/exhaust manifold to said first matable port of said supply/returnmanifold, said second control line pneumatically connecting said secondmatable port of said intake/exhaust manifold to said second matable portof said supply/return manifold, and said third control linepneumatically connecting said third matable port of said intake/exhaustmanifold to said third matable port of said supply/return manifold. 52.The modular retarder control valve of claim 51, and wherein saidmanifolds are fixed a predetermined distance apart with said first setof ports being diametrically opposed to said second set of ports, andeach of said control lines extends between said manifolds, said controlline having an expansion joint between its opposed ends to facilitatethe release and securement of said control line to said manifolds. 53.The modular retarder control valve of claim 52, and wherein saidmanifolds form facing parallel surfaces, and said matable ports arelocated at evenly spaced distances along said parallel surfaces, eachmating port in said intake/exhaust manifold has a corresponding matingport in said supply/return manifold that is located directly opposite,and each of said control lines being perpendicular to said parallelsurfaces of said manifold blocks.
 54. The modular retarder control valveof claim 53, and wherein at least two of said control lines have asubstantially equal length and are interchangeable.
 55. The modularretarder control valve of claim 54, and wherein each of saidinterchangeable fastening mechanisms is a like-shaped flange and boltassembly that is matingly received around one of said matable ports. 56.The modular retarder control valve of claim 55, and wherein each of saidmanifolds is an integral block.